Debugging basic BSP tasking functionality

[Matthew J Fletcher]

>If you put an explicit call to rtems_stack_checker_is_blown() in Init() at
>various points, does it think things are OK?

I put in a few and even the last one before the Init() task deletes itself
is ok.


>Just to be clear.. is this with the rtl22xx or rtl22xx_t BSP? The
non-thumb version
>uses -mapcs-frame which no other BSP uses. That makes me wonder.

rtl22xx_t 'Thumb', -mapcs-frame is passed on the gcc command line.


>Not with RTEMS. When you enter/exit an ISR, you go through some
>code which saves the proper registers, probably switches you to
>a dedicated stack, and does the OS stuff needed so it will do
>any needed dispatching at the end of the interrupt.

Is this shared between BSPs ? i tried to look for this and failed.




On 17 April 2013 15:34, Joel Sherrill <joel.sherrill at oarcorp.com> wrote:

>  On 4/17/2013 9:04 AM, Matthew J Fletcher wrote:
>
>  Hi,
>
>  Yes it the stack pointer out of range, because the current stack pointer
> returned by GCC _builtin_frame_XX in the IDLE thread looks like its
> actually that from the Init() thread.
>
>   You are completely in C code when this happens. There has been assembly
> to switch to the task initially (e.g. into _Thread_Handler) and if an
> interrupt
> occurred.
>
> If you put an explicit call to rtems_stack_checker_is_blown() in Init() at
> various points, does it think things are OK?
>
> It is easy for the stack not to be initialized to match gcc or gdb's
> expectation
> of how it ends.
>
> Just to be clear.. is this with the rtl22xx or rtl22xx_t BSP? The
> non-thumb version
> uses -mapcs-frame which no other BSP uses. That makes me wonder.
>
>  Thinking this through,my target is Thumb, so the C interrupt handler
> should be in a arm file with -mthumb-interwork set on the compile line.
>
>  I guess GCC can not auto-magicly know what particular functions are
> interrupts, so should there be some entry/exit functions to save/restore
> the stack, etc, like these...
>
>
> http://www.procyonengineering.com/embedded/arm/armlib/docs/html/group__processor__lpc2000.html
>
> ISR_ENTRY / ISR_EXIT
>
>
>   Not with RTEMS. When you enter/exit an ISR, you go through some
> code which saves the proper registers, probably switches you to
> a dedicated stack, and does the OS stuff needed so it will do
> any needed dispatching at the end of the interrupt.
>
> --joel
>
>
>
>
>
> On 17 April 2013 13:40, Sebastian Huber <
> sebastian.huber at embedded-brains.de> wrote:
>
>> On 04/17/2013 02:27 PM, Matthew J Fletcher wrote:
>>
>>>  >Here a context switch from the Init to the idle (I guess) thread
>>> happens.
>>>   The >_User_extensions_Thread_switch
>>>  >() is called before the context switch and the running thread is
>>> checked.  So
>>> a sp of >0x814d299c must be in the range of the Init stack area.
>>>
>>> Yes it is, Init() stack area is 0x814d1a70 -> 0x814d2a74 (4100 bytes).
>>> So it
>>> looks like the stack pointer is not getting adjusted correctly when task
>>> switching into a new thread ? as the rtems_idle task is using the Init()
>>> stack
>>> pointer.
>>>
>>
>>  Now I am a bit confused.  What check goes wrong in
>>
>>
>> Stack_check_Frame_pointer_in_range() at check.c:69 0x81180f6e
>> rtems_stack_checker_switch_extension() at check.c:276 0x81180f6e
>> _User_extensions_Thread_switch() at userextthreadswitch.c:41 0x8118cbaa
>> _Thread_Dispatch() at threaddispatch.c:128 0x8118bce6
>> _Thread_Enable_dispatch() at threaddispatch.c:59 0x8118bd5e
>> rtems_task_delete() at taskdelete.c:94 0x81189750
>> Init() at startup.c:241 0x81007840
>>
>>  ?
>>
>> In case the stack pointer is out of range, then I guess that the
>> interrupt exception processing is broken.  It is hard to know what happens
>> without an actual target.
>>
>>
>>
>>>  > nm your-app.exe | grep 'bsp_\(section\|stack\)' | sort
>>>
>>> No matches.
>>>
>>
>>  Ok, 4.10 uses the old linker command files.  These symbols are only
>> available in 4.11.
>>
>>
>> --
>> Sebastian Huber, embedded brains GmbH
>>
>> Address : Dornierstr. 4, D-82178 Puchheim, Germany
>> Phone   : +49 89 189 47 41-16 <%2B49%2089%20189%2047%2041-16>
>> Fax     : +49 89 189 47 41-09 <%2B49%2089%20189%2047%2041-09>
>> E-Mail  : sebastian.huber at embedded-brains.de
>> PGP     : Public key available on request.
>>
>> Diese Nachricht ist keine geschäftliche Mitteilung im Sinne des EHUG.
>>
>
>
>
> --
>
> regards
> ---
> Matthew J Fletcher
>
>
>
> --
> Joel Sherrill, Ph.D.             Director of Research & Development joel.sherrill at OARcorp.com        On-Line Applications Research
> Ask me about RTEMS: a free RTOS  Huntsville AL 35805
> Support Available                (256) 722-9985
>
>


-- 

regards
---
Matthew J Fletcher
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